JP2010512102A - Data packet transmission method and channel allocation method in wireless network - Google Patents

Abstract

As an example of a data packet transmission method in a wireless network, the present invention provides a bidirectional channel time including a first channel time block for transmitting a specific data packet and a second channel time block for receiving a response to the specific data packet. Requesting allocation of a block, transmitting a specific data packet through a first channel time block, and receiving a response to the specific data packet through a second channel time block, wherein the bidirectional channel time block comprises: Disclosed is a data packet transmission method which is preset so as to be allocated in a non-reserved area in a superframe.

Description

  The present invention relates to a wireless network, and more particularly to a method for transmitting data packets and a method for assigning channels in a wireless network.

  In recent years, with the development of communication, computer, and networking technologies, a wide variety of networks have been developed and implemented in real life. As for the network, there is a large-scale network that connects the whole world like a wired or wireless Internet, while a small-scale wired or wireless network that connects home appliances in a limited space such as a general home or work. Is also present. As the types of networks are diversified, interfacing techniques for connecting networks to each other or between devices to enable communication with each other are also diversifying.

  A specific device transmits a bandwidth request command to the coordinator in order to receive channel resources for data transmission on the network. Then, the coordinator checks whether there is a channel resource to be allocated to the device. If the channel resource is present, the coordinator allocates the requested channel resource to the device. In this case, information on channel resources allocated to the device, that is, timing allocation information is transmitted to the device in the WVAN through a beacon transmitted later.

  On the channel, command words, data streams, asynchronous data, etc. are transmitted through the reserved area, and control information, MAC command words, asynchronous data, etc. are transmitted between the coordinator and the device or between the devices. The above channel resource allocation method can be useful when transmitting a normal data stream, command word, or the like. However, there are certain restrictions on data or message transmission between devices, for example, when a certain device transmits a message to another device and then there is a time constraint already set until a response message is received from the other device. For example, a channel resource allocation method different from the above channel resource allocation method is desired.

  The present invention is to solve the above-described problems of the prior art, and its object is to satisfy certain restrictions when transmitting data or messages between devices in a wireless network. It is an object of the present invention to provide a channel resource allocation method that can be used.

  A method of transmitting a data packet in a wireless network according to an embodiment of the present invention includes a first channel time block for transmitting a specific data packet and a second channel time block for receiving a response to the specific data packet. Requesting allocation of a bidirectional channel time block including: transmitting the specific data packet through the first channel time block; and receiving a response to the specific data packet through the second channel time block. In addition, the bidirectional channel time block is preset to be allocated in a non-reserved area in a superframe.

  Preferably, the non-reserved area is maintained in a non-reserved state for the specific data packet.

  The non-reserved area may be used as a competition base when there is no allocation request for the specific data packet.

  The specific data packet may be associated with a Round Trip Time (RTT) _TEST.

  The bidirectional channel time block may be allocated in consideration of a round trip time when the specific data packet is transmitted and the response is received.

  The specific data packet may be received from an upper layer, and the upper layer may be one of an AVC protocol layer and a DTCP (Digital Transmission Content Protection) layer.

  According to another embodiment of the present invention, a method for transmitting a data packet in a wireless network simultaneously reserves a first transmission block for transmitting a first data packet and a second transmission block for transmitting a second data packet. And transmitting the first data packet through the first transmission block; and receiving the second data packet through the second transmission block, the first transmission block and the second transmission. At least one schedule period between blocks is determined based on a time interval in which the first data packet is transmitted and the second data packet is received.

  The first transmission block and the second transmission block are preset to be assigned to a non-reserved area that is maintained in a non-reserved state for the first data packet and the second data packet in a superframe. It is preferable.

  The non-reserved area may be used as a competition base when there is no allocation request for the first data packet and the second data packet.

  Each of the first data packet and the second data packet may be associated with an authentication key value.

  The second transmission block is preferably adjacent to the first transmission block.

  The at least one schedule period may include a maximum schedule period and a minimum schedule period.

  According to still another embodiment of the present invention, a method for allocating a communication channel in a wireless HD system including a coordinator and at least one device includes a first channel for transmitting a first message from a first device to the coordinator. Transmitting a request command for allocating a second channel for receiving a second message, receiving a response to the request command from the coordinator, and sending a response to the request to the second device. Transmitting the first message through a channel and receiving the second message from the second device through the second channel.

  The first channel and the second channel may be allocated in consideration of a time limit for transmitting the first message and receiving the second message.

  The first message may be a Round Trip Time (RTT) _TEST command, and the second message may be an RTT_TEST response command.

  The method may further include identifying a round trip time between the first message and the second message, and transmitting information on the round trip time to an upper layer.

  The upper layer may be one of an AVC protocol layer and a DTCP (Digital Transmission Content Protection) layer.

  According to the present invention, channel resources can be secured and time constraints can be satisfied stably in a situation where time constraints are set when a specific message is transmitted and received in a wireless network.

FIG. 2 shows an exemplary WVAN configured with multiple devices. FIG. 2 illustrates an exemplary superframe structure used in WVAN. FIG. 2 is a diagram illustrating an exemplary protocol hierarchy implemented in a WVAN device. It is a figure for demonstrating more specifically the transmission / reception process of a RTT_TEST (MAC1A) _CMD message and an ACCEPTED (MAC2B) _RSP message in a RTT test process. It is a figure for demonstrating the transmission / reception process of a RTT_TEST (MAC1A) _CMD message and an ACCEPTED (MAC2B) _RSP message in the RTT test process through the super frame used by WVAN. It is a flowchart which shows one preferable Example of this invention. 7 is a flowchart for explaining a process [S66] of performing a channel resource allocation procedure in FIG. It is a figure for demonstrating one suitable Example of this invention on a super-frame. It is a figure for demonstrating embodiment of this invention. It is a flowchart for demonstrating other embodiment of this invention.

  The embodiments described below are examples in which the technical features of the present invention are applied to a WVAN (Wireless Video Area Network) which is a kind of wireless network. WVAN uses WiHD (wireless HD) technology that can provide a throughput of 4.5 Gbps or higher so that a 1080p A / V stream can be transmitted without compression using a frequency band of 60 GHz within a short distance of 10 m. It is a wireless network to use.

  FIG. 1 is a diagram illustrating an example of a WVAN including a plurality of devices.

  A WVAN is a network configured for data exchange between devices located in a certain space. The WVAN is composed of two or more devices 10 to 14, one of which operates as a coordinator 10. The coordinator 10 is an apparatus that performs a function of allocating and scheduling radio resources so that a plurality of devices share a predetermined radio resource without collision when configuring a radio network between the devices. The coordinator periodically transmits a message including scheduling information in order to allocate and schedule radio resources and inform each device. This message is called a beacon in the following. The coordinator can transmit and receive data through at least one channel as a normal device, in addition to the function of allocating resources so that the devices constituting the network can communicate. It can also perform functions such as clocksynchronization, network subscription, and maintaining bandwidth resource.

  WVAN supports two types of physical layers (PHYs). That is, WVAN supports HRP (high-rate physical layer) and LRP (low-rate physical layer) as physical layers. HRP is a physical layer that can support a data transmission rate of 1 Gb / s or more, and LRP is a physical layer that supports a data transmission rate of several Mb / s. HRP is highly directional and is used for transmission of isochronous data stream, asynchronous data, MAC command and A / V control data through unicast connection. . The LRP supports a directional or omni-directional mode, and is used for transmitting beacons, asynchronous data, MAC command words including beacons through unicast or broadcasting. The HRP channel and the LRP channel share a frequency band and are used by being divided by the TDM method. HRP uses four channels with a 2.0 GHz bandwidth in the 57-66 GHz band, and LRP uses three channels with a 92 MHz bandwidth.

  FIG. 2 is a diagram for explaining an exemplary superframe structure used in WVAN.

  Referring to FIG. 2, each super frame includes a region 20 in which a beacon is transmitted, a reserved channel time block 22, and an unreserved channel time block 21. Become. Each channel time block (CTB) is time-divisioned into a region where data is transmitted through HRP (HRP region) and a region where data is transmitted through LRP (LRP region). The

  The beacon 20 is periodically transmitted by the coordinator. The introduction part of each superframe can be identified through the beacon. The beacon includes scheduled timing information, WVAN management and control information. Devices can exchange data over the network based on timing information and management / control information included in the beacon. The HRP region can be used by a device to which a coordinator has allocated a channel time in response to a device channel time allocation request to transmit data to another device.

  The reserved CTB area 22 is used when a device to which the coordinator has allocated a channel time in response to a request for channel time allocation of the device transmits data to other devices. Command words, data streams, asynchronous data, etc. can be transmitted through the CTB area. An HRP channel is used when a specific device transmits data to other devices through the reserved CTB region, and an LRP channel is used when a device receiving data transmits an acknowledgment signal (ACK / NACK) for the received data. Can be used.

  The non-reserved CTB region 21 can be used to transmit control information, MAC command words, asynchronous data, or the like between the coordinator and the device or between the devices. In order to prevent data collision between devices in the non-reserved CTB region, a CSMA (Carrier Sense Multiple Access) method or a slotted Aloha method can be applied. In this non-reserved CTB region, data can be transmitted only through the LRP channel. If there are a lot of control information and command words to be transmitted, it is possible to set a reserved area in the LRP channel. The length and number of reserved and non-reserved CTBs in each superframe can vary from one superframe to another and are controlled by the coordinator.

  Although not shown in FIG. 2, it includes a contention-based control period (CBCP) positioned following the beacon for transmitting an urgent control / management message. The interval length of CBCP is set so that a certain critical value (mMAXCBCPLen) is set and this critical value is not exceeded.

  FIG. 3 is a diagram illustrating an example of a protocol hierarchical structure implemented in a WVAN device.

  Referring to FIG. 3, the communication module 32 of each device 31 included in the WVAN can be divided into at least two layers according to its function, and generally, a PHY layer (not shown), a MAC It includes a hierarchy 33, an adaptation hierarchy, and a station management entity (SME) (not shown). The Adaptation layer includes at least two protocols: an AVC protocol 34 and an AV packetizer 35. The AVC protocol 34 can perform functions such as device control, connection control, device characteristics, and device capability. The AV packetizer 35 can take charge of a function of configuring AV data for providing the HRP data service.

  Each upper layer can provide a high-speed data service, a low-speed data service, a management service, and the like. High-speed data services support video, audio and data transmission. The low-speed data service supports an audio data MAC command, a small amount of asynchronous data, and the like. The SME (not shown) is an individual independent of the hierarchy, collects device state information in each hierarchy, and controls the lower hierarchy. It can also serve as a control interface between the host and the wireless device.

  Each hierarchy includes a hierarchy management entity. An individual that manages the MAC hierarchy is called an MLME (MAC Layer Management Entity), and an individual that manages the PHY hierarchy is called a PLME (PHY Layer Management Entity). Messages exchanged between different layers are called primitives, and the communication module is called a modem. Examples of primitives that can be used for communication through services access points (SAP) 37 and 38 include primitives such as request, indication, response, and confirm. .

  A request is used to request a process from a management individual. The indication is used for notifying a management individual of a state change in a local lower layer regardless of a request or information received from a peer management individual or a request from an upper layer. The response (response) is used to respond to a request from the peer management individual. Confirm is used to inform the management individual of the result of the previous request.

  The protocol layer can further include a layer for data transmission security and authentication, for example, a DTCP (Digital Transmission Content Protection) layer 36. In FIG. 3, this is configured in the AV packetizer 35, but it may naturally be configured separately. The DTCP layer 36 can perform a function of exchanging key values for authentication with each other, authenticating through them, and encrypting and transmitting the values. In the following description, the layer for security and authentication is described as the DTCP layer 36, but those skilled in the art can apply any other layer that can perform the same or similar function regardless of the name. I understand that.

  Hereinafter, a device that transmits or provides output data is referred to as a source device, and a device that receives output data and outputs it based on the function of each device is referred to as a sink device.

The embodiments described below are examples in which the technical features of the present invention are applied to an RTT (Round Trip Time) test for DTCP-IP (Supplement EDTCP Mapping to IP) on a WiHD system. The DTCP (Digital Transmission Content Protection) protocol is a protocol for preventing illegal copying of content during transmission and playback of a video stream, and “Digital Transmission Content Protection Specification Vol. 1 and Vol. 2” is defined as the standard.
DTCP is a protocol developed for the IEEE 1394 cable, and an additional localization (AL) process is added to extend it and use it for IP (Internet Protocol) in home networks such as WiHD. Is done. The reason why the additional regionalization process is necessary is that it is necessary to limit the use length in extending the DTCP protocol developed for the IEEE 1394 cable to the home network, and the device ID of the sink device stored in the source device This is because there is no (identification).
The source and / or sink device may check a round trip time (RTT) through RTT_TEST to determine whether the round trip time is greater than a preset critical value. The source device then stores the device ID of the sink device in the storage area of the source device, sets a timer, ensures that data such as content is transmitted within a specified time, checks the round trip time, and The key value can be exchanged depending on whether or not the round trip time is larger than a preset critical value. Preferably, the source device can exchange the key value only if the round trip time is not greater than a preset critical value.

The RTT test is performed to check whether the sink device that receives the data stream transmitted by the source device is an authenticated device. In the RTT test, the source device and the sink device go through a process of exchanging an authentication key (AKE: Authentication Key). As the RTT test process begins, the source device and the sink device exchange messages for preparing the RTT test. After exchanging messages for RTT test preparation, the source device transmits the encryption parameter 'N' to the sink device through the RTT_SETUP (N) _CMD message.
The source device and the sink device encrypt the shared authentication key (AKE) using the encryption parameter 'N' according to the following mathematical formulas 1 and 2, and calculate MAC1A and MAC2A, and MAC1B and MAC2B, respectively.
[Equation 1]
MAC1A = MAC1B = [SHA-1 (MK + N)] msb80
[Equation 2]
MAC2A = MAC2B = [SHA-1 (MK + N)] lsb80
The sink device transmits an ACCEPTED (N) _RSP message to the source device as a response to the RTT_SETUP (N) _CMD message.

  Thereafter, the source device transmits the calculated MAC1A to the sink device through the RTT_TEST (MAC1A) _CMD message, and the sink device transmits MAC2B through the ACCEPTED (MACK2B) _RSP message to the source device. Subsequently, the source device compares the MAC 2B received from the sink device with its calculated MAC 2A, and the sink device performs an RTT test through a process of comparing the MAC 1A received from the source device with its calculated MAC 1B. If the sink device is authenticated in this process, the source device adds the sink device to the RTT registry.

  In the above RTT test process, the time constraint that the source device should receive the ACCEPTED (MACK2B) _RSP message from the sink device within a time interval (eg, 7 ms) from the time when the source device transmitted the RTT_TEST (MAC1A) _CMD message. timelimit) is set. That is, if the ACCEPTED (MACK2B) _RSP message cannot be received within 7 ms from the time when the RTT_TEST (MAC1A) _CMD message is transmitted, the process is performed again from the process of transmitting the RTT_SETUP (N) _CMD message.

  FIG. 4 is a diagram for specifically explaining a transmission / reception process of the RTT_TEST (MAC1A) _CMD message and the ACCEPTED (MAC2B) _RSP message in the RTT test process.

  In FIG. 4, a layer or entity for DTCP-IP is implemented in the source device and sink device of WVAN. The layer or entity for DTCP-IP may be embodied by being included in the DME of the source device and the sink device, or may be embodied in another upper layer or entity. In FIG. 4, it is assumed that a layer or entity for DTCP-IP is implemented in DME.

  Referring to FIG. 4, the DME of the source device transmits an RTT_TEST_CMD.MPD to indicate that it transmits an RTT_TEST (MAC1A) _CMD message. The req primitive is transmitted to the MAC / MLME of the source device [S41]. The MAC / MLME of the source device transmits the RTT_TEST (MAC1A) _CMD message to the sink device [S42]. The MAC / MLME of the sink device is RTT_TEST_CMD. The ind primitive is transmitted to the DME of the sink device to notify that the RTT_TEST (MAC1A) _CMD message has been received [S43].

  The DME of the sink device transmits RTT_TEST_CMD. To the MAC / MLME of the sink device. An rsp primitive is transmitted, and an ACCEPTED (MAC2B) _RSP message is transmitted as a response to the RTT_TEST (MAC1A) _CMD message [S44]. The MAC / MLME of the sink device transmits an ACCEPTED (MAC2B) _RSP message to the source device [S45]. The MAC / MLME of the source device informs the DME of the source device that the RTT_TEST_CMD.MPD has received the ACCEPTED (MAC2B) _RSP message. The cfm primitive is transmitted [S46].

  In FIG. 4, 'RTT' indicates that the DME of the source device is RTT_TEST_CMD. rt primitive is transmitted to the MAC / MLME of the source device and RTT_TEST_CMD. It can be defined as a time limit to the point in time when a cfm primitive is to be received. Further, the MAC / MLME of the source device can be defined as a time limit from the time when the RTT_TEST (MAC1A) _CMD message is transmitted to the sink device to the time when the ACCEPTED (MAC2B) _RSP message should be received. Of course, the MAC / MLME of the sink device is RTT_TEST_CMD. RTT_TEST_CMD. from the time when the ind primitive is transmitted to the DME of the sink device. It can be defined as a time limit to the point in time when an rsp primitive is to be received.

  In the present embodiment, 'RTT' indicates that the DME of the source device is RTT_TEST_CMD. rt primitive is transmitted to the MAC / MLME of the source device and RTT_TEST_CMD. Suppose that it is defined as a time limit to the time when the cfm primitive is to be received and is set to 7 ms.

  'MaxTI' receives the ACCEPTED (MAC2B) _RSP message from the sink device from the time when the MAC / MLME of the source device transmits the RTT_TEST (MAC1A) _CMD message to the sink device to the extent that the above time limit can be satisfied. It means the maximum time interval (MaximumTime Interval) to the power point. 'MaxTI' is set in consideration of the above time limit (RTT) and the data processing time for message transmission in the source device.

  ‘MinTI’ is a limit that can satisfy the time limit (RTT), and the sink device MAC / MLME sends the RTT_TEST_CMD. From the point where the ind primitive is transmitted, RTT_TEST_CMD. It means the minimum time interval (MinimumTime Interval) that takes until the time of receiving the rsp primitive.

  In FIG. 4, the DME of the source device is RTT_TEST_CMD. rt primitive is transmitted, and then within the time limit (RTT), RTT_TEST_CMD. In order to receive the cfm primitive, the source device transmits ACCEPTED from the sink device at an interval larger than the minimum time interval (MinTI) and smaller than the maximum time interval (MaxTI) from the time when the source device transmitted the RTT_TEST (MAC1A) _CMD message to the sink device. It is preferable that channel resources that can receive the (MAC2B) _RSP message are guaranteed. Also, the time limit (RTT) can have the same value as the maximum time interval (MaxTI) or the minimum time interval (MinTI) by definition.

  FIG. 5 is a diagram for explaining the above situation through a superframe used in WVAN.

  The length of this super frame is 20 ms. In the figure, in order to satisfy the time limit (RTT), the source device must transmit the RTT_TEST (MAC1A) _CMD message to the sink device within the “A” period, and the sink device within the “B” period. ACCEPTED (MAC2B) _RSP message must be received.

  When a message is transmitted / received in a contention-based manner, it is not possible to ensure that the above condition is satisfied. Therefore, a channel resource for transmitting / receiving the message must be allocated to the source device or the sink device. At this time, it is possible to receive one continuous channel resource, that is, a plurality of continuous CTBs, within a range that satisfies the above-described conditions, but this leads to waste of channel resources. Therefore, in the embodiment according to the present invention, the first channel resource (a) for transmitting the RTT_TEST (MAC1A) _CMD message from the source device to the sink device and the first channel resource (a) are separated, and the sink device It is conceivable to receive a second channel resource (b) for transmitting an ACCEPTED (MAC2B) _RSP message from the device to the source device. In WVAN, the first and second channel resources mean at least one CTB.

  FIG. 6 is a flow chart illustrating a preferred embodiment of the present invention.

  In FIG. 6, an authentication key exchange process between the source device and the sink device [S61], a message exchange process for preparing the RTT test [S62], and the source device transmitting an RTT_SETUP (N) _CMD message to the sink device [ S63] calculating the MAC1A and MAC2A, MAC1B and MAC2B in the source device and the sink device (S64), and transmitting the ACCEPTED (N) _RSP message from the sink device to the source device [S65] As described in the process. However, FIG. 6 is different in that some primitive transmission processes between internal layers for transmitting each message between the source device and the sink device are added.

  The source device that has received the ACCEPTED (N) _RSP message performs a procedure of receiving channel resources required for exchanging the RTT_TEST (MAC1A) _CMD message and the ACCEPTED (MAC2B) _RSP message with the sink device [S66]. This channel resource allocation procedure is performed between the source device and the coordinator of the WVAN.

  The channel resource allocation process [S66] will be specifically described below with reference to FIG. After the source device receives the channel resource in the channel resource allocation process [S66], the source device transmits an RTT_TEST (MAC1A) _CMD message to the sink device using the received first channel resource [S67]. The sink device receives the RTT_TEST (MAC1A) _CMD message and transmits the ACCEPTED (MAC2B) _RSP message to the source device using the allocated second channel resource as a response to the RTT_TEST (MAC1A) _CMD message [S68]. In this case, since the sink device also receives the beacon broadcast by the coordinator, the allocation information of the second channel resource can be acquired, and thus the ACCEPTED (MAC2B) _RSP message can be transmitted using the second channel resource. .

  FIG. 7 is a flowchart showing the process [S66] for performing the channel resource allocation procedure.

  Referring to FIG. 7, the DME of the source device transmits MLME-ADD-STREAM. The req primitive is transmitted, and an instruction is made to request allocation of channel resources required for exchanging the RTT_TEST (MAC1A) _CMD message and the ACCEPTED (MAC2B) _RSP message [S71]. The MAC / MLME of the source device transmits a BW request message (bandwidth request command) to the coordinator [S72]. The BW request message includes information indicating that the requested channel resource is a channel resource for transmission of an RTT test, that is, an RTT_TEST (MAC1A) _CMD message and an ACCEPTED (MAC2B) _RSP message.

  Table 1 shows an example of the data format of the BW request message.

表２は、表１の各‘BW request item’フィールドのデータフォーマットの一例である。

Table 2 is an example of the data format of each “BW request item” field of Table 1.

表２で、SchedulePeriodは、同一のスケジューリングに割り当てられる少なくとも二つのチャネル時間ブロックのそれぞれの開始する時間差を意味するもので、表２に示すように、最小値のMinimumSchedule Periodと最大値のMaximum Schedule Periodで知らせることができる。

In Table 2, SchedulePeriod means the time difference between the start of each of at least two channel time blocks allocated to the same scheduling, and as shown in Table 2, the minimum value Minimum Schedule Period and the maximum value Maximum Schedule Period. You can let me know.

  Table 3 shows an example of the data format of the “RequestControl” field in Table 2.

表３で、‘Bi-directional’フィールドは、要請されるチャネル資源がソースデバイスの立場でメッセージの送信及び受信のための両方向（bi-directional）のチャネル資源、すなわち、第１チャネル資源及び第２チャネル資源であることを表示するフィールドである。例えば、‘Bi-directional’フィールドが‘１’に設定されると両方向チャネル資源を意味し、‘０’に設定されると、一つの連続したチャネル資源を意味すると約束することができる。その逆の場合も可能である。

In Table 3, the 'Bi-directional' field indicates that the requested channel resource is a bi-directional channel resource for transmitting and receiving messages from the source device, ie, the first channel resource and the second channel resource. This field indicates that it is a channel resource. For example, when the 'Bi-directional' field is set to '1', it means a bidirectional channel resource, and when it is set to '0', it can be promised to mean one continuous channel resource. The reverse case is also possible.

  When receiving the BW request message from the source device, the coordinator MAC / MLME informs the coordinator DME of MLME-ADD-STREAM. The ind primitive is transmitted [S73]. The DME of the coordinator checks whether the channel resource requested by the source device, that is, the first channel resource and the second channel resource can be allocated [S74]. If possible, the requested channel resource is transmitted to the source device. Decide to assign to.

  At this time, the positions of the first channel resource and the second channel resource on the superframe, the spacing (spacing), and the respective section lengths are preset to values fixed in the WVAN. For example, when a specific WVAN is first formed, information related to the position, arrangement interval, and section length on the superframe of the first channel resource and the second channel resource may be shared between devices through the signaling of the coordinator. it can.

  When there is a request for allocation of the first channel resource and the second channel resource from a specific device in the WVAN in the above method, the coordinator displays only the availability of the allocation of the first channel resource and the second channel resource to the specific device and transmits it. Thus, when allocation is possible, the specific device can transmit and receive a message using information on the first channel resource and the second channel resource that are known in advance. While the first channel resource and the second channel resource are not allocated to the specific device, it can be used as another application, for example, as a non-reserved CTB in a competitive system.

  In FIG. 7, the coordinator DME informs the coordinator MAC / MLME that the requested channel resource can be allocated to the source device by MLME-ADD-STREAM. The rsp primitive is transmitted [S75]. The coordinator MAC / MLME transmits a BW response message (bandwidth response command) in which the 'Reason Code' field is displayed as 'SUCCESS' to the source device [S76]. The MAC / MLME of the source device is MLME-ADD-STREAM. With the 'Reason Code' field displayed as 'SUCCESS' in the DME of the source device. The cfm primitive is transmitted to inform that the requested channel resource can be allocated [S77].

  The coordinator DME sends the MLME-BEACON.NET to the coordinator MAC / MLME for beacon broadcast for a specific superframe. The req primitive is transmitted [S78]. The coordinator MAC / MLME broadcasts a beacon to the WVAN [S79]. This broadcast beacon includes allocation information of all channel resources in the superframe including allocation information related to the first channel resource and the second channel resource allocated to the source device and the sink device. The allocation information regarding the first channel resource and the second channel resource includes information regarding whether the first channel resource and the second channel resource can be allocated.

  Table 4 is an example of a data format of a beacon used in WVAN.

ＷＶＡＮの各デバイスに割り当てられるチャネル資源と関連した情報は、ビーコンに‘Reserved Schedule IE’の形態で含まれる。表５は、ビーコンに含まれる‘Reserved Schedule IE’のデータフォーマットの一例である。

Information related to channel resources allocated to each device of the WVAN is included in a beacon in the form of 'Reserved Schedule IE'. Table 5 is an example of a data format of 'Reserved Schedule IE' included in the beacon.

表６は、表５の‘Scheduleblock’フィールドのデータフォーマットの一例である。

Table 6 is an example of the data format of the “Scheduleblock” field in Table 5.

表６で、‘StreamIndex’フィールドは、該当のチャネル資源割当と関連したストリーム（stream）を指示する情報を含む。表７は、表６の‘Schedule info’フィールドのデータフォーマットの一例である。

In Table 6, the 'StreamIndex' field includes information indicating a stream associated with the corresponding channel resource allocation. Table 7 is an example of the data format of the “Schedule info” field in Table 6.

表７で、‘ScrID’フィールドは、チャネル資源が割り当てられるソースデバイスの識別情報（ID）を含み、‘DestID’フィールドは、シンクデバイスの識別情報を含む。‘Static’フィールドは、割り当てられるスケジュールブロックが静的（static）スケジュールか或いは動的（dynamic）スケジュールかを表す情報を含み、‘PHYmode’フィールドは、ＨＲＰモードを使用するか或いはＬＲＰモードを使用するかを表す情報を含む。‘Beam formed’フィールドは、ビームフォーミング（beamforming）が用いられるか否かを表す情報を含む。‘Bi-directional’フィールドは、割当要請されたチャネル資源、すなわち、第１チャネル資源及び第２チャネル資源の割当可否を表す情報を含む。

In Table 7, the 'ScrID' field includes identification information (ID) of a source device to which channel resources are allocated, and the 'DestID' field includes identification information of a sink device. The 'Static' field contains information indicating whether the assigned schedule block is a static schedule or a dynamic schedule, and the 'PHYmode' field uses the HRP mode or the LRP mode. Contains information that represents The 'Beam formed' field includes information indicating whether or not beamforming is used. The 'Bi-directional' field includes information indicating whether allocation of channel resources requested for allocation, that is, allocation of the first channel resource and the second channel resource is allowed.

  Upon receiving this beacon, the source device MAC / MLME sends the MLME-BEACON. An ind primitive is transmitted [S70].

  FIG. 8 is a diagram for explaining a preferred embodiment of the present invention on a superframe.

  In the figure, the position, arrangement interval, and section length of the first channel resource and the second channel resource in the superframe have fixed values. However, the first channel resource and the second channel resource have different uses depending on whether or not they are assigned to a specific device. That is, when the first channel resource and the second channel resource are not allocated to the specific device as in the (N−1) th superframe or the (N + 1) th superframe in FIG. 8, the first channel resource and The second channel resource can be used by any device in the same manner as a general non-reserved CTB.

  On the other hand, in the same figure, when the first channel resource and the second channel resource are allocated in response to the channel resource allocation request of the specific device as in the case of the Nth superframe, the first channel resource and the second channel resource The channel resource becomes a reserved CTB and can only be used by the specific device to which it is assigned. In the figure, it is preferable that the arrangement interval (BCS) between the first channel resource and the second channel resource is larger than the minimum time interval (MinTI) and smaller than the maximum time interval (MaxTI).

  FIG. 9 is a diagram for explaining an embodiment of the present invention.

  With reference to FIG. 9, an exemplary method for considering queuing delay and channel access delay is described.

  As an exemplary method for reducing the channel approach delay, a transmission resource for transmitting a specific data packet, eg, an RTT_TEST data packet, eg, a channel time block (CTB) is reserved in advance, and the RTT_TEST data is transmitted through the reserved CTB. A packet is transmitted. At this time, there is a method of simultaneously reserving a first CTB used for transmission and a second CTB used for reception. This can be referred to as a bidirectional BW reservation method.

  With this method, it is possible to prevent transmission and reception from being delayed by reserving at least two CTBs having an appropriate interval at a time in consideration of the round trip time. This is based on the premise that transmission in one direction is possible through one CTB. If transmission in both directions is possible through one CTB, the time interval considering the round trip time is guaranteed. If so, it is possible to reserve one CTB.

  Referring to FIG. 9, a process of reserving a CTB used for transmitting / receiving an RTT_TEST data packet in Part # 1 (90), that is, a CTB for transmission / reception is shown. When the RTT_SETUP data packet is transmitted to the MAC layer of the source device for the CTB reservation for transmitting and receiving the RTT_TEST data packet in the DTCP layer of the source device, the CTB for transmitting and receiving the RTT_TEST data packet is reserved in the coordinator (or sink device). Transmit the requested message or data. The MAC layer of the coordinator that has received this transmits this to the DTCP layer of the coordinator.

  Then, the DTCP layer of the coordinator confirms it, assigns a CTB for transmitting / receiving the RTT_TEST data packet, includes information on the allocated CTB or acceptance / rejection in the RTT_SETUP_RSP data packet, includes the MAC layer of the coordinator, the MAC of the source device Sequentially transmit or transmit to the DTCP layer of the layer and source device (92). The source device may confirm the CTB reservation information from the received RTT_SETUP_RSP, or may confirm the CTB reservation information through a beacon broadcast later.

  A process of transmitting and receiving an RTT_TEST data packet through the CTB reserved in the reservation process in PART # 2 (91) will be described as follows. RTT_TEST data packet is transmitted and received through the reserved CTB (93, 94). In this case, the RTT_TEST data packet can be received within the preset time.

  In the MAC layer, at least one data packet can be received not only from the DTCP layer but also from other upper layers, for example, the AV packetizer layer. In this case, even if a CTB for RTT_TEST data packet transmission / reception is reserved, transmission is performed in the order received in the MAC layer, and data packets previously received in the MAC layer are transmitted. The reserved CTB cannot be used. That is, there is a risk of queuing delay. For example, the RTT_TEST data packet may not be transmitted using the expected CTB reserved by the above queue delay during the PART # 2 (91) process. Therefore, it is possible to identify the RTT_TEST data packet in the MAC layer and perform the bidirectional BW reservation method more effectively.

  FIG. 10 is a flowchart for explaining another embodiment of the present invention.

  The above-described data packet transmission method and bi-directional BW reservation method can be performed in combination and / or a combination thereof. With reference to FIG. 10, a case will be described in which a data packet is identified and transmitted regardless of the reception order and a bidirectional BW reservation method is used in combination.

  The process described below is applicable not only to transmitting the RTT_TEST data packet described as an example but also any other data packet or message.

  The transmission block for transmission and the transmission block for reception of the RTT_TEST data packet are reserved [S100]. Of course, if transmission and reception can be performed in both directions using one transmission block, one transmission block may be reserved.

  In the MAC layer, an RTT_TEST data packet is received [S101]. At this time, not only the RTT_TEST data packet but also a plurality of other data packets may be received. Each received data packet is confirmed to identify the RTT_TEST data packet [S102]. As a method for identifying a data packet, a method of transmitting the identification information together and using the same, a method of using priority information, a method of using a physically or logically partitioned buffer, and the like can be applied. .

  If it is identified that one data packet is an RTT_TEST data packet, the transmission transmission block and the reception transmission block reserved in step S100 are searched or confirmed [S103]. This can be confirmed from a broadcast beacon, a received message, a response message received during the reservation process, or the like. The MAC layer transmits the data packet through a transmission block for transmission [S104]. Then, the MAC layer receives the data packet through the reception transmission block within the preset time [S105]. This completes an exemplary process for checking the round trip time.

  Each procedure shown in FIG. 10 may be performed entirely, or only a part thereof may be performed, and the order of the illustrated procedure is not involved. In addition, some procedures may be performed in advance prior to performing the embodiment of the present invention, and other partial procedures may be performed under assumption.

  The foregoing detailed description of the preferred embodiments of the present invention has been provided to enable any person skilled in the art to implement and practice the invention. Although the foregoing has been described with reference to the preferred embodiments of the present invention, those skilled in the art will recognize that the invention is within the spirit and scope of the invention as defined by the following claims. It will be understood that the present invention can be modified and changed in various ways. For example, although the present invention has been described centering on the RTT_TEST data packet, the method of the present invention can be applied to any data packet. Further, in the above-described embodiment, even if it is not a round-trip message, the present invention can be similarly applied to a case where fast transmission is attempted without delay.

  In the above embodiment, the constituent elements and features of the present invention are combined in a predetermined form. Each component or feature should be considered optional unless stated otherwise. Each component or feature may be implemented in a form that is not combined with other components or features, and some components and / or features may be combined to form an embodiment of the present invention. The order of operations described in the embodiments of the present invention can be changed. Some configurations or features of one embodiment may be included in other embodiments, or may be replaced with corresponding configurations or features of other embodiments. In addition, it is obvious that claims that do not have an explicit citation relationship in the claims can be combined to constitute an embodiment, or can be included as new claims by amendment after application.

  Embodiments according to the present invention may be implemented by various means such as hardware, firmware, software, or a combination thereof. When implemented in hardware, embodiments of the present invention include one or more application specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), fieldprogrammable FPGAs (FPGAs). gate arrays), processor, controller, microcontroller, microprocessor, etc.

  In the case of implementation by firmware or software, an embodiment of the present invention may be implemented in the form of a module, procedure, function, or the like that performs the functions or operations described above. The software code can be stored in a memory unit and driven by a processor. This memory unit is located inside or outside the processor and can exchange data with the processor by various known means.

  The terms used above can be replaced with different ones. For example, a device is a user device (or equipment), a station, etc., a coordinator is a coordinator (or control) device, a coordinating (or control) device, a coordinator (or control) station, a coordinator, It can be used by changing to a PNC (Piconetcoordinator) or the like.

  The present invention can be applied to a wireless communication system and a wireless HD system. The present invention provides an embodiment of a data packet transmission method that can reduce data packet transmission delay using a bidirectional reservation method.

Claims (18)

A method for transmitting data packets over a wireless network, comprising:
Requesting allocation of a bidirectional channel time block including a first channel time block for transmitting a specific data packet and a second channel time block for receiving a response to the specific data packet;
Transmitting the specific data packet through the first channel time block;
Receiving a response to the specific data packet through the second channel time block;
The data packet transmission method according to claim 1, wherein the bidirectional channel time block is set in advance so as to be allocated in a non-reserved area in a superframe.   The method of claim 1, wherein the non-reserved area is maintained in a non-reserved state for the specific data packet.   The method of claim 1, wherein the non-reserved area is used as a competition base when there is no allocation request for the specific data packet.   The method of claim 1, wherein the specific data packet is associated with Round Trip Time (RTT) _TEST.   The method of claim 1, wherein the bidirectional channel time block is allocated in consideration of a round trip time when the specific data packet is transmitted and the response is received. .   The method of claim 1, wherein the specific data packet is received from an upper layer.   The method of claim 6, wherein the upper layer is one of an AVC protocol layer and a DTCP (Digital Transmission Content Protection) layer. A method for transmitting data packets over a wireless network, comprising:
Simultaneously reserving a first transmission block for transmitting a first data packet and a second transmission block for transmitting a second data packet;
Transmitting the first data packet through the first transmission block;
Receiving the second data packet through the second transmission block;
Including
At least one schedule period between the first transmission block and the second transmission block is determined based on a time interval in which the first data packet is transmitted and the second data packet is received. A data packet transmission method.   The first transmission block and the second transmission block are preset to be assigned to a non-reserved area that is maintained in a non-reserved state for the first data packet and the second data packet in a superframe. The data packet transmission method according to claim 8, wherein:   The method of claim 9, wherein the non-reserved area is used as a competitive basis when there is no allocation request for the first data packet and the second data packet.   The method of claim 8, wherein each of the first data packet and the second data packet is associated with an authentication key value.   The data packet transmission method of claim 8, wherein the second transmission block is adjacent to the first transmission block.   The data packet transmission method according to claim 8, wherein the at least one schedule period includes a maximum schedule period and a minimum schedule period. A method of allocating a communication channel in a wireless HD system including a coordinator and at least one device comprising:
Transmitting a request command for allocation of a first channel for transmitting a first message and a second channel for receiving a second message from the first device to the coordinator;
Receiving a response to the request command from the coordinator;
Transmitting the first message over the first channel to a second device;
Receiving the second message from the second device through the second channel;
Including a channel allocation method.   The channel allocation according to claim 14, wherein the first channel and the second channel are allocated in consideration of a time limit in which the first message is transmitted and the second message is received. Method.   The method of claim 14, wherein the first message is a Round Trip Time (RTT) _TEST command, and the second message is an RTT_TEST response command. Identifying a round trip time between the first message and the second message;
Transmitting information on the round trip time to an upper layer;
The channel allocation method according to claim 14, further comprising:   The channel allocation method according to claim 17, wherein the upper layer is one of an AVC protocol layer and a DTCP (Digital Transmission Content Protection) layer.

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